1. Field of the Invention
The present invention relates to a motor, and particularly, to a core-coil assembly of a motor and its manufacturing method capable of improving productivity and efficiency of an inner teeth type motor in which teeth parts around which a coil is wound are disposed inwardly.
2. Description of the Background Art
In general, a motor is used as a core driving source of most electronic and electrical products, such as a compressor, a washing machine and an electric fan. Improving productivity is increasingly considered as a main issue in production of such a motor. Here, one of main problems in improving productivity in a manufacturing process is generated when a coil is wound.
A motor can be commonly divided into an outer teeth type and an inner teeth type according to a position of teeth parts around which a coil is wound.
In the outer teeth type motor, a coil is wound in an outer winding method in which the coil is wound from an outer side of the teeth part while, in the inner teeth type motor, a coil is wound in an inner winding method in which the coil is wound from an inner side of the teeth part.
Generally, in the inner teeth type motor, the teeth parts around which a coil is wound are used as a stator, and a rotor comprised of a permanent magnet or a core around which another coil is wound is located therein. In case of an inner teeth type, it is difficult to wind a coil. For this reason, a separate core method is widely used, in which a core-coil assembly is manufactured by separately manufacturing a yoke part and a teeth part of a core, winding a coil around the teeth part and assembling the coil wound teeth part with the yoke part. For instance, U.S. Pat. No. 6,573,632B2 discloses a kind of a separate core method.
An assembling method for an inner teeth type core-coil assembly in accordance with another conventional art similar to the above-mentioned art is depicted in FIGS. 1 and 2. FIG. 1 is a perspective view showing a conventional inner teeth type core-coil assembly, and FIG. 2 is its plan view.
As shown, the conventional inner teeth type core-coil assembly 1 includes a yoke part 10 formed by stacking(laminating) ring-shaped core thin boards one upon another to form a magnetic path; and a few teeth parts 20 formed by stacking “T”-shaped core thin boards one upon another and radially coupled onto an inner circumferential surface of the yoke part 10, so that a coil (C) is wound therearound.
A teeth insertion groove 25 in which the teeth part 20 is inserted is formed in an inner circumferential surface of the yoke part 10 in a stepped manner.
One end of the teeth part 20 is formed in a stepped manner, corresponding to the teeth insertion groove 25 of the yoke part 10, and its other end is extendingly formed as a pole portion 30 with an arc shape.
A bobbin 35 having a quadrangular column shape and made of a insulation material is inserted onto an outer circumferential surface of a middle portion of the teeth part 20 in its longitudinal direction.
A coil (C) is wound around an outer circumferential surface of the bobbin 35, and both ends of the bobbin 35 are extendingly formed to be higher than a height of its coil(C)-wound body so that the winding coil (C) may not be deviated.
However, in such a separate core method, the teeth parts 20 are individually manufactured, the coil (C) is wound around each teeth part 20, and the coil wound teeth parts are individually assembled with the yoke part 10. For this reason, a manufacturing time and an assembling process are delayed, thereby deteriorating productivity.
In addition, inconvenience may occur because the coil (C) wound around each teeth part 20 should be connected on a separate printed circuit board (PCB) by an electrical means, soldering or the like after the assembling operation.
Besides, when each teeth part 20 is inserted in the teeth insertion groove 25, the pole portions 30 may not form a perfect circle because of an assembly error generated due to fine differences in shape. Accordingly, in this case, when a permanent magnet or the like is inserted in the core-coil assembly 1, a constant distance between the permanent magnet or the like and the pole portion 30 is not achieved, thereby causing a torque change due to a change of flux in operation of a motor.